<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>太阳系</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        body{
            background: url("imgs/solarsystem.jpg");
        }
        ul{
            width: 600px;
            height: 600px;
            margin:50px auto;
            position: relative;

        }
        @keyframes solar {
            from{
                transform: translate(-50%,-50%)  rotate(0deg);
            }
            to{
                transform:translate(-50%,-50%)  rotate(360deg);
            }
        }
        ul > li{
            list-style: none;
            position: absolute;
            left:50%;
            top:50%;
            transform: translate(-50%,-50%);
            border-radius: 50%;
            box-sizing: border-box;
            animation: solar linear infinite;
        }
        ul > li >span{
            width: 12px;
            height: 12px;
            border-radius: 6px;
            background-color: #fff741;
            position: absolute;
            left: 50%;
            top: 0;
            animation: solar 2s linear infinite;
        }
        ul > li:nth-child(1){/*太阳*/
            width: 60px;
            height: 60px;
            background-color: #fff741;
            box-shadow: 0px 0px 50px #fff741;
        }
        ul > li:nth-child(2){/*水星*/
            width: 120px;
            height: 120px;
            border: 2px solid #394057;
            animation-duration: 2s;
        }
        ul > li:nth-child(3){/*金星*/
            width: 180px;
            height: 180px;
            border: 2px solid #394057;
            animation-duration: 4s;
        }
        ul > li:nth-child(4){/*地球*/
            width: 240px;
            height: 240px;
            border: 2px solid #394057;
            animation-duration: 8s;
            background-size: 240px 240px;
        }
        ul > li >span > span{
            width: 6px;
            height: 6px;
            border-radius: 3px;
            background-color: blue;
            position: absolute;
            left: 3px;
            top: -10px;
        }
        ul > li:nth-child(5){/*火星*/
            width: 300px;
            height: 300px;
            border: 2px solid #394057;
            animation-duration: 12s;
        }
        ul > li:nth-child(6){/*木星*/
            width: 360px;
            height: 360px;
            border: 2px solid #394057;
            animation-duration: 16s;
        }
        ul > li:nth-child(7){/*土星*/
            width: 420px;
            height: 420px;
            border: 2px solid #394057;
            animation-duration: 25s;
        }
        ul > li:nth-child(8){/*天王星*/
            width: 480px;
            height: 480px;
            border: 2px solid #394057;
            animation-duration: 30s;
        }
        ul > li:nth-child(9){/*海王星*/
            width: 540px;
            height: 540px;
            border: 2px solid #394057;
            animation-duration: 40s;
        }
        ul > li:nth-child(10){/*银河系*/
            width: 600px;
            height: 600px;
            border: 2px solid #394057;
            animation-duration: 50s;
        }
    </style>
</head>
<body>
<ul>
    <li></li>
    <li><span></span></li>
    <li><span></span></li>
    <li><span></span><span></span></li>
    <li><span></span></li>
    <li><span></span></li>
    <li><span></span></li>
    <li><span></span></li>
    <li><span></span></li>
    <li><span></span></li>
</ul>

</body>
</html>